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Quorum Sensing Signals Form Complexes with Ag+ and Cu2+ Cations
Eric McGivney1,2, Kayleigh Elizabeth Jones3, Bandrea Weber1
1Department of Civil and Environmental Engineering , Carnegie Mellon University , Pittsburgh , Pennsylvania , United States.
ACS Chemical Biology
|March 7, 2018
Summary
Metal cations like silver (Ag+) and copper (Cu2+) bind to bacterial quorum sensing (QS) signals (HHL). This complexation inhibits QS activity and reduces metal toxicity, offering new strategies for controlling bacterial behavior.
Area of Science:
- Bacterial communication and signaling
- Metal-microbe interactions
- Biochemistry and molecular biology
Background:
- Quorum sensing (QS) controls critical bacterial functions, including virulence and biofilm formation.
- QS signal stability is affected by environmental factors.
- N-hexanoyl-L-homoserine lactone (HHL) is a key QS autoinducer signal.
Purpose of the Study:
- To investigate the novel complexation between metal cations (Ag+, Cu2+) and the QS signal HHL.
- To elucidate the molecular interactions and binding characteristics.
- To assess the impact of these complexes on QS activity and metal bioavailability in vivo.
Main Methods:
- Mass spectrometry
- Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR)
- Computational simulations
- In vivo experiments with Chromobacterium violaceum CV026
Main Results:
- HHL forms stable 1:1 complexes with Ag+ (Kd = 3.41 × 10-4 M) and Cu2+ (Kd = 1.40 × 10-5 M).
- Coordination occurs via oxygen moieties on the HHL molecule.
- Sublethal Ag+ and Cu2+ concentrations significantly reduced HHL-regulated QS activity.
- Preincubation of Ag+ with HHL decreased Ag+ toxicity to bacteria by tenfold.
Conclusions:
- Metal cations Ag+ and Cu2+ can complex with the QS signal HHL, altering its properties.
- This complexation effectively inhibits bacterial QS pathways.
- HHL:metal complexes modulate the bioavailability and toxicity of both the signal and the metal ions, suggesting potential applications in controlling bacterial infections.
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